Steam injection and flash heat treatment of isoelectric soy slurries

Abstract

A process for preparing a soy protein product having a high concentration of both solubilized carbohydrates and soluble protein, and being characterized by substantial freedom from bacterial activity, absence of objectionable beany flavor, light color, suitability for use in food preparations for human consumption, and enhanced palatability, wherein soybean material in the form of an aqueous slurry is first adjusted to an acid pH in the isoelectric range for the protein content of the material treated, or from about pH 3.5 to about pH 5.5, then subjected to steam injection to bring the temperature of the treated mass to the range of from about 225.degree. to about 400.degree. F, maintaining such temperature for a short time period, preferably from about 3 to about 30 seconds, to destroy viable bacteria and to solubilize carbohydrates. Residual steam is flashed, together with volatile constituents including objectionable flavor elements present in the soybean material. Thereafter, the pH of the hot steam-treated material is promptly adjusted upwardly to a value in the range of about pH 6 to about pH 10.5 to deter and to minimize protein denaturation. The end product, consisting of a viscous or semi-viscous dispersible fluid of milky appearance, may then be dried, as by spray drying, to provide a readily redispersible powder.